Optimizing humidity in aircraft

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CAREERS @ CTT

Dry facts

AN AIRCRAFT CABIN IS THE MOST DEHYDRATING PUBLIC ENVIRONMENT OF ALL KIND

Extremely dry air onboard aircraft

During flight humidity gradually decreases in the cabin to 5 – 15% RH. As a reference: Humidity in inhabited places on Earth is in the range of 20 – 100% RH. 
 
  • First Class often has around 5% RH and Business Class 5 – 10% RH.
  • Cockpit is even worse with almost 0% RH (no moisture content in the air!).
 

Cabin air in airplanes without continous humidity boost from an active humidification system will always be unhealthfully dry for humans. Air must be fresh with enough oxygen (read: low level of carbon dioxide). Therefore air is re-circulated with approx. 50% and mixed in with fresh air. But air at cruising altitude has no humidity. Consequently, air gradually gets more dry as fresh air intake exchanges humid ground air with super dry air.

The only source adding humidity is people onboard. Most long-haul aircraft offer different classes with different seat-density. The humidity level varies in the aircraft due to the fact that environmental control systems are dividing the aircraft into sections with dedicated supply and exhaust of air. In practise, the air is the driest in sections with lower passenger density (read: passenger paying the most suffer the most from dyr air issues such as impaired taste, sleeping disorders and dry air induced fatigue).

DRY AIR SYMPTOMS

Dehydration is a degenerative process with symptoms as listed below:

  • The taste in the mouth changes
  • The viscosity of saliva changes
  • The mucous membranes swell
  • The volatility of odor molecules decrease
  • The nasal cavity dries quickly
  • The ability to vaporize in the nose decreases
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OUR WELLNESS ONBOARD IN FOCUS

Humidity in air is an important condition for comfort climate.

  • Humidity is vital for our immune system

  • Humidity is better for our relax and sleep quality

  • Humidity increases our wellbeing and wellness

  • Humidity improves our sense to taste

  • Humidity reduces electrostatic electricity

 
“DRY AIR DOESN’T HELP OUR SENSE OF SMELL, EITHER. TYPICALLY, ODORANTS ARE TRANSPORTED TO OLFACTORY RECEPTORS IN THE NOSE VIA THE MUCUS LINING. WHEN THE NASAL CAVITY IS DRIED OUT, THE EFFICIENCY AT WHICH ODORANTS ARE DETECTED BY THE BRAIN IS REDUCED. WHEN YOU LOSE THE OLFACTORY COMPONENT,” EXPLAINS FINGER, “YOU LOSE MUCH OF THE FLAVOR COMPONENT OF FOOD.”
Dr. Tom Finger
Professor at the University of Colorado School of Medicine and co-director of the Rocky Mountain Taste and Smell Center (Source NBC)
Our body has adapted to the levels found on earth; ideally a humidity between 20 – 60 % RH. In winter time, humidity in our homes and workplaces can be 20 – 25 RH. This is considered dry but it is within our experience range and our body can handle it. When humidity drops to 15 – 20 percent RH the discomfort increases due to unchartered dryness with no evolutionary adaption (read: not common on Earth).
Humidity in an aircraft – significantly below Earth-range – affects how we feel. Although, it can be difficult to pinpoint exactly what is wrong. 
Wellbeing, taste, smell and the ability to relax and recover are weakened. Difficulty to sleep occurs and the risk of catching a cold increases. At extremely low humidity below 10 percent RH, these effects become more apparent; driven by dehydration of our mucous membranes, skin and eyes. 

Our taste changes and is different in the sky. Taste is taste buds and smell. Even short time exposure to extremely dry air affects the nose and mouth.

Actually up to 80% of what we consider taste is actually derived from smell.

The taste is built up around many very complex co-existing factors.